Ring-opened azlactone photoiniferters for radical polymerization

ABSTRACT

Photoiniferters for controlled radical polymerizations are described. The photoiniferters have an aziactone or ring-opened azlactone moiety to provide telechelic (co)polymers.

FIELD OF THE INVENTION

[0001] The present invention provides photoiniferters for radicalpolymerization processes and telechelic polymers made thereby.

BACKGROUND

[0002] In conventional radical polymerization processes, thepolymerization terminates when reactive intermediates are destroyed orrendered inactive; radical generation is essentially irreversible. It isdifficult to control the molecular weight and the polydispersity(molecular weight distribution) of polymers produced by conventionalradical polymerization, and difficult to achieve a highly uniform andwell-defined product. It is also often difficult to control radicalpolymerization processes with the degree of certainty necessary inspecialized applications, such as in the preparation of end functionalpolymers, block copolymers, star (co)polymers, and other noveltopologies.

[0003] In a controlled radical polymerization process radicals aregenerated reversibly, and irreversible chain transfer and chaintermination are absent. There are four major controlled radicalpolymerization methodologies: atom transfer radical polymerization(ATRP), reversible addition-fragmentation chain transfer (RAFT),nitroxide-mediated polymerization (NMP) and iniferters, each methodhaving advantages and disadvantages.

[0004] The term “iniferter”, or “photoiniferter” as it is also known,refers to a chemical compound that has a combined function of being afree radical initiator, transfer agent, and terminator, the term“iniferter” being a word formed by the underlined portions of the termsidentifying these functions. The photo portion of the term indicatesthat the polymerization is photolytically induced. This term and its usein the production of block copolymers is well known, particularlybecause of the work of Takayuki Otsu of the Department of AppliedChemistry, Osaka City University, Osaka, Japan. This work is discussed,for example, in an article by Otsu et al entitled “Living RadicalPolymerizations in Homogeneous Solution by Using Organic Sulfides asPhotoiniferters”, Polymer Bulletin, 7, 45-50 (1982), an article by Otsuet al entitled “Living Mono-and Biradical Polymerizations in HomogeneousSystem Synthesis of AB and ABA Type Block Copolymers”, Polymer Bulletin,11, 135-142 (1984), Otsu entitled “Iniferter Concept and Living RadicalPolymerization”, J. Polymer Science, Pat A, vol. 38, 2121-2136 (2000),and in European Patent Application No. 88303058.7, Publication No. 0 286376, publication date Oct. 12, 1988.

[0005] There is a need for a radical polymerization process whichprovides (co)polymers having a predictable molecular weight and a narrowmolecular weight distribution (low “polydispersity”). A further need isstrongly felt for a radical polymerization process which is sufficientlyflexible to provide a wide variety of products, but which can becontrolled to the degree necessary to provide highly uniform productswith a controlled structure (i.e., controllable topology, composition,stereoregularity, etc.). There is further need for a controlled radicalpolymerization process which provides telechelic (co)polymers capable ofentering into further polymerization or functionalization throughreactive end-groups, particularly electrophilic end groups.

SUMMARY OF THE INVENTION

[0006] The present invention provides photoiniferters for controlledradical polymerization processes that comprise compounds of the formula:

[0007] wherein

[0008] R¹ and R² are each independently selected from H, an alkyl group,a nitrile group, a cycloalkyl group, a heterocyclic group, an arenylgroup and an aryl group, or R¹ and R² taken together with the carbon towhich they are attached form a carbocyclic ring;

[0009] R³ and R⁴ are each independently selected from an alkyl group, acycloalkyl group, an aryl group, an arenyl group, or R³ and R⁴ takentogether with the carbon to which they are attached form a carbocyclicring;

[0010] R⁵ and R⁶ are each independently selected from an alkyl group, acycloalkyl group, an aryl group, an arenyl group, or R⁵ and R⁶ takentogether with the nitrogen to which they are attached form aheterocyclic ring, R⁵ and R⁶ are optionally substituted with phosphate,phosphonate, sulfonate, ester, halogen, nitrile, amide, and hydroxygroups; R⁵ and R⁶ may optionally be substituted with one or morecaternary heteroatoms, such as oxygen, nitrogen or sulfur;

[0011] Q is a linking group selected from a covalent bond, an arenylgroup, an aryl group (—CH₂—)_(o), —CO—O—(CH₂)_(n)—,—CO—O—(CH₂CH₂O)_(o)—, —CO—NR⁸—(CH₂)_(o)—, —CO—S—(CH₂)_(o)—, where o is 1to 12, and R⁸ is H, an alkyl group, a cycloalkyl group, an arenyl groupor an aryl group; and

[0012] n is 0 or 1.

[0013] The present invention also provides photoiniferters that comprisethe ring-opened reaction product of the photoiniferters of Formula I anda reactive compound, such as an aliphatic compound, having one or morenucleophilic groups. Such photoiniferters have the general formula:

[0014] wherein

[0015] R¹ and R² are each independently selected from H, a nitrilegroup, an alkyl group, a cycloalkyl group, an arenyl group, aheterocyclic group and an aryl group or R¹ and R² taken together withthe carbon to which they are attached form a carbocyclic ring;

[0016] R³ and R⁴ are each independently selected from an alkyl group, acycloalkyl group, an aryl, an arenyl group, or R³ and R⁴ taken togetherwith the carbon to which they are attached form a carbocyclic ring;

[0017] R⁵ and R⁶ are each independently selected from an alkyl group, acycloalkyl group, an aryl group, an arenyl group, or R and R takentogether with the nitrogen to which they are attached form aheterocyclic ring, R and R are optionally substituted with phosphate,phosphonate, sulfonate, ester, halogen, nitrile, amide, and hydroxygroups; R⁵ and R⁶ may optionally be substituted with one or morecaternary heteroatoms, such as oxygen, nitrogen or sulfur;

[0018] n is 0 or 1;

[0019] Z is O, S or NR⁸, wherein R⁸ is H, an alkyl group, a cycloalkylgroup, an arenyl group, a heterocyclic group or an aryl group;

[0020] R⁷ is an organic or inorganic moiety and has a valency of m, R⁷is the residue of a mono- or polyfunctional compound of the formulaR⁷(ZH)_(m);

[0021] Q is a linking group selected from a covalent bond, an arylgroup, an arenyl group, (—CH₂—)_(o), —CO—O—(CH₂)_(n)—,—CO—O—(CH₂CH₂O)_(o)—, —CO—NR⁸—(CH₂)_(o)—, —CO—S—(CH₂)_(o)—, where o is 1to 12, and R⁸ is H, an alkyl group, a cycloalkyl group, an aryl group,an arenyl group, a heterocyclic group or an aryl group;

[0022] m is an integer of at least 1, preferably at least 2.

[0023] The photoiniferters of the present invention provide (co)polymershaving a predictable molecular weight and a narrow molecular weightdistribution. Advantageously, the photoiniferters provide novelmultireactive addition polymers having first and second terminalreactive groups that may be used for further functionalization. Thepresent invention further provides a controlled radical polymerizationprocess useful in the preparation of terminal-functionalized(telechelic) (co)polymers, block copolymers, star (co)polymers, graftcopolymers, and comb copolymers. The process provides these (co)polymerswith controlled topologies and compositions.

[0024] The control over molecular weight and functionality obtained inthis invention allows one to synthesize numerous materials with manynovel topologies for applications in coatings, surface modifications,elastomers, sealants, lubricants, pigments, personal care compositions,composites, inks, adhesives, water treatment materials, hydrogels,imaging materials, telechelic materials and the like.

[0025] In another aspect, the invention provides a method forpolymerization of one or more olefinically unsaturated monomerscomprising addition polymerizing one or more olefinically unsaturatedmonomers using the photoiniferter comprising the azlactonephotoiniferters, or the ring-opened azlactone photoiniferter.

[0026] It is to be understood that the recitation of numerical ranges byendpoints includes all numbers and fractions subsumed within that range(e.g. 1 to 5 includes 1, 1.5, 2, 2.75, 3, 3.80, 4, and 5).

[0027] It is to be understood that all numbers and fractions thereof arepresumed to be modified by the term “about.”

[0028] It is to be understood that “a” as used herein includes both thesingular and plural.

[0029] The general definitions used herein have the following meaningswithin the scope of the present invention.

[0030] The term “alkyl” refers to straight or branched, cyclic oracyclic hydrocarbon radicals, such as methyl, ethyl, propyl, butyl,octyl, isopropyl, tert-butyl, sec-pentyl, cyclohexyl, and the like.Alkyl groups include, for example, 1 to 18 carbon atoms, preferably 1 to12 carbon atoms, or most preferably 1 to 6 carbon atoms.

[0031] The term “aryl” means the monovalent residue remaining afterremoval of one hydrogen atom from an aromatic compound which can consistof one ring, two or three fused or catenated rings having 6 to 14 carbonatoms.

[0032] The term “arenyl” means the monovalent residue remaining afterremoval of a hydrogen atom from the alkyl portion of a hydrocarboncontaining both alkyl and aryl groups having 6 to 26 atoms, optionallysubstituted with one or more catenary heteroatoms.

[0033] The term “azlactone” means 2-oxazolin-5-one groups and2-oxazolin-6-one groups of Formula I, where n is 0 and 1, respectively.

[0034] The term “heterocyclic group” or “heterocycle” means themonovalent residue remaining after removal of one hydrogen atom from ancycloaliphatic or aromatic compound having one, two or three fused ringshaving 5 to 12 ring atoms and 1 to 3 heteroatoms selected from S, N, andnonperoxidic O. Useful heterocycles include azlactone, pyrrole, furan,thiophene, imidazole, pyrazole, thiazole, oxazole, pyridine, piperazine,piperidine, and hydrogenated and partially hydrogenated derivativesthereof

[0035] The term “multifunctional” means the presence of more than one ofthe same functional reactive group;

[0036] The term “multireactive” means the presence of two or more of twodifferent functional reactive groups;

[0037] The term “polyfunctional” is inclusive of multireactive andmultifunctional.

[0038] The term “acid catalyst” or “acid catalyzed” means catalysis by aBrønsted—or Lewis-acid species;

[0039] The term “molecular weight” means number average molecular weight(M_(n)), unless otherwise specified.

[0040] The term (co)polymer refers to homo- and copolymers.

[0041] The term (meth)acrylate refers to both methacrylate and acrylate.

DETAILED DESCRIPTION

[0042] The present invention provides novel photoiniferters of Formula Iand the corresponding ring-opened photoiniferters of Formula II forcontrolled radical polymerization processes.

[0043] wherein

[0044] R¹ and R² are each independently selected from H, an alkyl groupof 1 to 18 carbon atoms, a nitrile, a cycloalkyl group having 3 to 14carbon atoms, an aryl group having 6 to 14 ring atoms, an arenyl grouphaving 6 to 26 carbon atoms, a heterocyclic group having one, two orthree fused rings having 5 to 12 ring atoms and 1 to 3 heteroatomsselected from S, N, and nonperoxidic 0; or R¹ and R² taken together withthe carbon to which they are attached form a carbocyclic ring containing4 to 12 ring atoms.

[0045] R³ and R⁴ are each independently selected from an alkyl grouphaving 1 to 18 carbon atoms, a cycloalkyl group having 3 to 14 carbonatoms, an aryl group having 6 to 14 ring atoms, an arenyl group having 6to 26 carbon atoms and 0 to 3 S, N, and nonperoxidic O heteroatoms, orR³ and R⁴ taken together with the carbon to which they are attached forma carbocyclic ring containing 4 to 12 ring atoms;

[0046] R⁵ and R⁶ are each independently selected from an alkyl group, acycloalkyl group, an aryl group, an arenyl group, or R⁵ and R takentogether with the nitrogen to which they are attached form aheterocyclic ring, R⁵ and R⁶ are optionally substituted with phosphate,phosphonate, sulfonate, ester, halogen, nitrile, amide, and hydroxygroups; R⁵ and R⁶ may optionally be substituted with one or morecaternary heteroatoms, such as oxygen, nitrogen or sulfur;

[0047] Z is O, NH, S or NR⁸, wherein R⁸ is a H, an alkyl group, acycloalkyl group, an aryl group an arenyl group or a heterocyclic group;

[0048] R⁷ is an organic or inorganic moiety and has a valency of m;

[0049] m is an integer of at least 1, preferably 1 to 8, most preferablyat least 2;

[0050] Q is a linking group selected from a covalent bond, an arylgroup, an arenyl group, (—CH₂—)_(o), —CO—O—(CH₂)_(n)—,—CO—O—(CH₂CH₂O)_(o)—, —CO—NR⁸—(CH₂)_(n)—, —CO—S—(CH₂)_(n)—, where o is 1to 12, and R⁸ is H, an alkyl group, a cycloalkyl group or an aryl group;and n is 0 or 1.

[0051] Examples of olefinically unsaturated monomers that may bepolymerized include (meth)acrylates such as ethyl(meth)acrylate,propyl(meth)acrylate, butyl(meth)acrylate, isooctyl(meth)acrylate andother alkyl(meth)acrylates; also functionalized (meth)acrylatesincluding glycidyl(meth)acrylate, poly(ethyleneoxide) (meth)acrylate,trimethoxysilyl propyl(meth)acrylate, allyl(meth)acrylate,hydroxyethyl(meth)acrylate, hydroxypropyl(meth)acrylate, mono- anddialkyl aminoalkyl(meth)acrylates; mercaptoalkyl(meth)acrylates,fluoroalkyl(meth)acrylates; (meth)acrylic acid, fumaric acid (andesters), itaconic acid (and esters), maleic anhydride; styrene, α-methylstyrene; vinyl halides such as vinyl chloride and vinyl fluoride;acrylonitrile, methacrylonitrile; vinylidene halides; butadienes;unsaturated alkylsulphonic acids or derivatives thereof;2-vinyl-4,4-dimethylazlactone, N-vinyl pyrrolidinone, and(meth)acrylamide or derivatives thereof. Mixtures of such monomers maybe used. Monomers having pendent, nucleophilic functional groups such ashydroxy-, amino- or thiol-functional groups are particularly useful forproviding so-called AB_(n) polymers. Such pendent nucleophilicfunctional groups may react with the azlactone terminal group to providenovel architectures. Such pendent nucleophilic functional groups may beprotected during the polymerization, and deprotected post-polymerizationfor providing novel polymer architecture.

[0052] Photoiniferters of Formula I may be prepared using thegeneralized sequence as shown:

[0053] In the above Scheme I, where X and X′ are halogen atoms or othersuitable leaving groups, an amino acid is first acylated, generally bydissolving the amino acid in aqueous base, followed by treatment withthe acyl halide compound under interfacial reaction conditions.Cyclization may be effected by treatment with acetic anhydride andpyridine, by treatment with carbodiimides, or preferably by treatmentwith ethyl chloroformate and a trialkylamine, which proceeds through amixed carboxylic-carbonic anhydride. The dithiocarbamate moiety isintroduced by displacement of the X group. Further details regarding thepreparation of azlactones may be found in “Polyazlactones”, Encyclopediaof Polymer Science and Engineering, vol. 11, 2^(nd) Ed., John Wiley andSons, pp. 558-571 (1988). With respect to the above reaction scheme, itwill be apparent that diacyl halide starting materials may be used toproduce dimeric or bis-azlactone photoiniferters. These bis-azlactonephotoiniferters have the general structure:

[0054] wherein

[0055] DiTC is a dithiocarbamate group of the formula R⁵R⁶N—C(S)—S—,

[0056] R¹ is selected from H, an alkyl group of 1 to 18 carbon atoms, acycloalkyl group having 3 to 14 carbon atoms, an aryl group having 6 to14 ring atoms, an arenyl group having 6 to 26 carbon atoms, aheterocyclic group having one, two or three fused rings having 5 to 12ring atoms and 1 to 3 heteroatoms selected from S, N, and nonperoxidic0;

[0057] R³ and R⁴ are each independently selected from an alkyl grouphaving 1 to 18 carbon atoms, a cycloalkyl group having 3 to 14 carbonatoms, an aryl group having 6 to 14 ring atoms, an arenyl group having 6to 26 carbon atoms and 0 to 3 S, N, and nonperoxidic 0 heteroatoms, orR³ and R⁴ taken together with the carbon to which they are attached forma carbocyclic ring containing 4 to 12 ring atoms;

[0058] R⁵ and R⁶ are each independently selected from an alkyl group, acycloalkyl group, an aryl group, an arenyl group, a heterocyclic group,or R⁵ and R⁶ taken together with the nitrogen to which they are attachedform a heterocyclic ring, R⁵ and R⁶ are optionally substituted withphosphate, phosphonate, sulfonate, ester, halogen, nitrile, amide, andhydroxy groups; R⁵ and R⁶ may optionally be substituted with one or morecaternary heteroatoms, such as oxygen, nitrogen or sulfur;

[0059] R⁹ is a divalent alkylene group of 1 to 18 carbon atoms, acycloalkylene group having 3 to 14 carbon atoms, an aryl group having 6to 14 ring atoms, a heterocyclic group, or an arenyl group having 6 to26 carbon atoms,

[0060] Q is a linking group selected from a covalent bond, (—CH₂—)_(o),—CO—O—(CH₂)_(o)—, —CO—O—(CH₂CH₂O)_(o)—, —CO—NR⁸—(CH₂)_(n)—,—CO—S—(CH₂)_(o)—, where o is 1 to 12, and R⁸ is H, an alkyl group, acycloalkyl group, an arenyl group, a heterocyclic group or an arylgroup;

[0061] and o is 0 or 1.

[0062] Useful azlactone photoiniferters include the following compounds:

[0063] R=Me, CN or Ph

[0064] Ring-opened azlactone compounds of Formula II may be made bynucleophilic addition of a compound of the formula R⁷(ZH)_(m) to theazlactone carbonyl of Formula I as shown below. In the Scheme I¹, R⁷ isan inorganic or organic group having one or a plurality of nucleophilic-ZH groups, which are capable of reacting with the azlactone moiety ofFormula I. R⁷(ZH)_(m) may be water.

[0065] Alternatively, such ring opened compounds may be prepared bynucleophilic addition of a compound of the formula R⁷(ZH)_(m) to thehalogen-containing (“X”) azlactone, followed by displacement of the Xgroup with the dithiocarbamate, as shown in Scheme III.

[0066] If organic, R⁷ may be a polymeric or non-polymeric organic groupthat has a valence of m and is the residue of a nucleophilicgroup-substituted compound, R⁷(ZH)_(m), in which Z is —O—, —S—, or —NRwherein R⁸ can be a H, an alkyl, a cycloalkyl or aryl, a heterocyclicgroup, an arenyl and m is at least one, preferably at least 2. Theorganic moiety R has a molecular weight up to 20,000, preferablyselected from mono- and polyvalent hydrocarbyl (i.e., aliphatic and arylcompounds having 1 to 30 carbon atoms and optionally zero to fourheteroatoms of oxygen, nitrogen or sulfur), polyolefin, polyoxyalkylene,polyester, polyolefin, poly(meth)acrylate, or polysiloxane backbones. Ifinorganic, R⁷ may comprise silica, alumina or glass having one or aplurality of -ZH groups on the surface.

[0067] In one embodiment, R⁷ comprises a non-polymeric aliphatic,cycloaliphatic, aromatic or alkyl-substituted aromatic moiety havingfrom 1 to 30 carbon atoms. In another embodiment, R⁷ comprises apolyoxyalkylene, polyester, polyolefin, poly(meth)acrylate, orpolysiloxane polymer having pendent or terminal reactive -ZH groups.Useful polymers include, for example, hydroxyl, thiol or aminoterminated polyethylenes or polypropylenes, hydroxyl, thiol or aminoterminated poly(alkylene oxides) and poly(meth)acylates having pendantreactive functional groups, such as hydroxyethyl acrylate polymers andcopolymers.

[0068] Depending on the nature of the functional group(s) of R⁷(ZH)_(m),a catalyst may be added to effect the condensation reaction. Normally,primary amine groups do not require catalysts to achieve an effectiverate. Acid catalysts such as trifluoroacetic, ethanesulfonic, andtoluenesulfonic acids are effective with hydroxyl groups and secondaryamines.

[0069] With respect to the compound R⁷(ZH)_(m), m is at least one, butpreferably m is at least two. The multiple -ZH groups of thepolyfunctional compound may be the same or different. Multifunctionalcompounds may be reacted with the azlactone compound of Formula I toproduce polyfunctional photoiniferters of Formula II, where m is atleast two. Such polyfunctional photoiniferters allow the preparation ofgraft, branched, and star (co)polymers and other useful topologies.

[0070] Useful alcohols of the formula R⁷(ZH)_(m) include aliphatic andaromatic monoalcohols and polyols. Useful monoalcohols include methanol,ethanol, octanol, decanol, and phenol. The polyols useful in the presentinvention include aliphatic or aromatic polyols having at least twohydroxyl groups. Examples of useful polyols include ethylene glycol,propylene glycol, butanediol, 1,3-pentane diol, 2,2-oxydiethanol,hexanediol, poly(pentyleneadipate glycol), poly(tetramethylene etherglycol), poly(ethylene glycol), poly(caprolactone diol),poly(1,2-butylene oxide glycol), trimethylol ethane, trimethylolpropane, trimethyol aminomethane, ethylene glycol, 2-butene-1,4-diol,pentaerythritol, dipentaerythritol, and tripentaerythritol. The term“polyol” also includes derivatives of the above-described polyols suchas the reaction product of the polyol with di- or poly-isocyanate, ordi- or poly-carboxylic acid, the molar ratio of polyol to —NCO, or —COOHbeing 1 to 1.

[0071] Useful amines of the formula R⁷(ZH)_(m) include aliphatic andaromatic monoamines and polyamines. Any primary or secondary amine maybe employed, although primary amines are preferred to secondary amines.Useful monoamines include, for example, methyl-, ethyl-, propyl-,hexyl-, octyl, dodecyl-, dimethyl-, methyl ethyl-, and aniline. The term“di-, or polyamine,” refers to organic compounds containing at least twonon-tertiary amine groups. Aliphatic, aromatic, cycloaliphatic, andoligomeric di- and polyamines all are considered useful in the practiceof the invention. Representative of the classes of useful di- orpolyamines are 4,4′-methylene dianiline,3,9-bis-(3-aminopropyl)-2,4,8,10-tetraoxaspiro[5,5]undecane, andpolyoxyethylenediamine. Many di- and polyamines, such as those justnamed, are available commercially, for example, those available fromHuntsman Chemical, Houston, Tex. The most preferred di- or polyaminesinclude aliphatic diamines or aliphatic di- or polyamines and morespecifically compounds with two primary amino groups, such as ethylenediamine, hexamethylene diamine, dodecanediamine, and the like.

[0072] Useful thiols of the formula R⁷(ZH)_(m) include aliphatic andaromatic monothiols and polythiols Useful alkyl thiols include methyl,ethyl and butyl thiol, as well as 2-mercaptoethanol,3-mercapto-1,2-propanediol, 4-mercaptobutanol, mercaptoundecanol,2-mercaptoethylamine, 2,3-dimercaptopropanol,3-mercaptopropyltrimethoxysilane, 2-chloroethanethiol,2-amino-3-mercaptopropionic acid, dodecyl mercaptan, thiophenol,2-mercaptoethyl ether, and pentaerythritol tetrathioglycolate. Usefulsoluble, high molecular weight thiols include polyethylene glycoldi(2-mercaptoacetate), LP-3™ resins supplied by Morton Thiokol Inc.(Trenton, N.J.), and Permapol P3 ™ resins supplied by Products Research& Chemical Corp. (Glendale, Calif.) and compounds such as the adduct of2-mercaptoethylamine and caprolactam.

[0073] The invention provides multifunctional photoiniferters of FormulaII, whereby an azlactone photoiniferter of Formula I is ring-opened by amultireactive or multifunctional compound of the formula R⁷(ZH)_(m),where m is at least 2. Such multifunctional photoiniferters may be usedto produce branched, star and graft (co)polymers and other topologies.It will also be apparent that such (co)polymers may also be prepared byfirst polymerizing a monomer using the photoiniferter of Formula I, toproduce polymers having an azlactone group at one terminal end, and thensubsequently reacting the polymers with a polyfunctional compound of theformula R⁷(ZH)_(m), where m is at least 2.

[0074] In another embodiment, the multifunctional photoiniferters maycomprise a solid support having a plurality of photoiniferter moietieson the surface thereof. Such photoiniferter-functionalized supports havethe general structure (corresponding to Formula II):

[0075] wherein DiTC, R¹, R², R³, R⁴, Q, Z, n and m are as previouslydescribed for Formula II and SS is a solid support corresponding to R⁷.The solid support material includes functional groups to whichphotoiniferter molecules of Formula I can be covalently attached forbuilding large or small organic compounds. Useful functional groupsinclude hydroxyl, amino and thiol functional groups corresponding to-ZH.

[0076] The support material can be organic or inorganic. It can be inthe form of solids, gels, glasses, etc. It can be in the form of aplurality of particles (e.g., beads, pellets, or microspheres), fibers,a membrane (e.g., sheet or film), a disc, a ring, a tube, or a rod, forexample. Preferably, it is in the form of a plurality of particles or amembrane. It can be swellable or non-swellable and porous or nonporous.

[0077] The support material can be a polymeric material that can be usedin conventional solid phase synthesis. It is chosen such that it isgenerally insoluble in the solvents or other components used insynthetic reactions that occur during the course of solid phasesynthesis.

[0078] Examples of useable pre-existing support materials are describedin G. B. Fields et al., Int. J. Peptide Protein Res., 35, 161 (1990) andG. B. Fields et al., in Synthetic Peptides: A User's Guide, G. A. Grant,Ed., pages 77-183, W.H. Freeman and Co., New York, N.Y. (1992). Thesupport material is in the form of an organic polymeric material, suchas polystyrenes, polyalkylenes, nylons, polysulfones, polyacrylates,polycarbonates, polyesters, polyimides, polyurethanes, etc. and havinghydroxyl, amino or thiol substituents on the surface. For pre-existingsupport materials, a preferred support material is polystyrene.

[0079] In the present polymerization, the amounts and relativeproportions of photoiniferter and monomer are those effective to conductradical polymerization. Accordingly, the amount of photoiniferter can beselected such that the photoiniferter concentration is from 10⁻⁵M to 1M, preferably 10⁻⁴ to 10⁻² M. Alternatively, the photoiniferter can bepresent in a molar ratio of from 10⁻⁵:1 to 10⁻¹:1, preferably from10⁻⁵:1 to 2×10⁻³:1, relative to monomer.

[0080] The present polymerization may be conducted in bulk, or in asolvent. Solvents, preferably organic, can be used to assist in thedissolution of the photoiniferter in the polymerizable monomers, and asa processing aid. Preferably, such solvents are not reactive with theazlactone group. Suitable solvents include ethers such as diethyl ether,ethyl propyl ether, dipropyl ether, methyl t-butyl ether, di-t-butylether, glyme (dimethoxyethane), diglyme, diethylene glycol dimethylether; cyclic ethers such as tetrahydrofuran and dioxane; alkanes;cycloalkanes; aromatic hydrocarbon solvents such as benzene, toluene,o-xylene, m-xylene, p-xylene; halogenated hydrocarbon solvents;acetonitrile; lactones such as butyrolactone, and valerolactones;ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone,cyclopentanone, and cyclohexanone; sulfones such as tetramethylenesulfone, 3-methylsulfolane, 2,4-dimethylsulfolane, butadiene sulfone,methyl sulfone, ethyl sulfone, propyl sulfone, butyl sulfone, methylvinyl sulfone, 2-(methylsulfonyl)ethanol, and 2,2′-sulfonyldiethanol;sulfoxides such as dimethyl sulfoxide; cyclic carbonates such aspropylene carbonate, ethylene carbonate and vinylene carbonate;carboxylic acid esters such as ethyl acetate, Methyl Cellosolve™ andmethyl formate; and other solvents such as methylene chloride,nitromethane, acetonitrile, glycol sulfite and mixtures of suchsolvents, and supercritical solvents (such as CO₂). The presentpolymerization may be conducted in accordance with known polymerizationprocesses.

[0081] The photoiniferter is caused to dissociate to form free radicalsby exposure to an appropriate radiant energy source. The particularenergy source and its intensity are selected to result in dissociationof the photoiniferter to free radicals. When employing a photoiniferterthat will dissociate upon exposure to ultraviolet light radiation, anultraviolet light source is utilized. When employing a photoiniferterthat will dissociate upon exposure to visible light radiation, a visiblelight source is utilized. A visible light source is preferably usedsince it is more convenient and is considered less hazardous. Theintensity and rate of radiation is chosen so that it will advance thepolymerization at a reasonable rate without deleteriously affecting thepolymer segment being produced. A light source having a wavelength onthe order of 200 to 800 nm spaced approximately 10 cm from the reactantsto provide an exposure of 1.25 milliwatts per square centimeter has beenfound to produce suitable results. If the energy source is ultravioletradiation, a suitable ultraviolet light transparent vessel is utilized.

[0082] A mixture of the polymerizable monomer(s), and the photoinifertermay be irradiated with activating UV radiation. UV light sources can beof two types: 1) relatively low light intensity sources such asblacklights which provide generally 10 mW/cm² or less (as measured inaccordance with procedures approved by the United States NationalInstitute of Standards and Technology as, for example, with a UVIMA™ UM365 L-S radiometer manufactured by Electronic Instrumentation &Technology, Inc., in Sterling, Va.) over a wavelength range of 280 to400 nanometers and 2) relatively high light intensity sources such asmedium pressure mercury lamps which provide intensities generallygreater than 10 mW/cm², preferably between 15 and 450 mW/cm². Whereactinic radiation is used to fully or partially crosslink the polymercomposition, high intensities and short exposure times are preferred.For example, an intensity of 600 mW/cm² and an exposure time of about 1second may be used successfully. Intensities can range from about 0.1 toabout 150 mW/cm², preferably from about 0.5 to about 100 mW/cm², andmore preferably from about 0.5 to about 50 mW/cm².

[0083] Upon exposure to the energy source, the photoiniferterdissociates to form free radicals that promote free radicalpolymerization. Upon completion of the free radical polymerization ofthe free radically polymerizable monomer, the energy source isdiscontinued to permit the free radically polymerized segments torecombine with the terminator portion of the photoiniferter to formpolymer segments. A second monomer charge may then be introduced ifdesired, which is free radically polymerizable to the block A′, and thenew mixture is exposed to the energy source to cause dissociation of theterminator radical and free radical polymerization of the second monomercharge onto the first polymer segment, that now being the photoiniferterof the second free radical polymerization. Upon completion ofpolymerization of the second monomer charge, the energy source isterminated and the terminator portion of the photoiniferter recombineswith the polymer block to provide a block copolymer

[0084] Polymerizing may be conducted at a temperature of from −78 to200° C., preferably from 0 to 160° C. and most preferably from 0 to 30°C. The reaction should be conducted for a length of time sufficient toconvert at least 1% of the monomer to polymer. Typically, the reactiontime will be from several minutes to 5 days, preferably from 30 minutesto 3 days, and most preferably from 1 to 24 hours.

[0085] Polymerizing may be conducted at a pressure of from 0.1 to 100atmospheres, preferably from 1 to 50 atmospheres and most preferably atambient pressure (although the pressure may not be measurable directlyif conducted in a sealed vessel). An inert gas such as nitrogen or argonmay be used.

[0086] If desired, the polymerization may be accelerated by the additionof a metal compound to the reaction mixture. Useful accelerants includemetal compounds represented by the general formula M_(y)L_(z) wherein Mis a cation having a valency of z of a metal which is selected from thegroup consisting of tin, zinc, cobalt, titanium, palladium, and lead; yis an integer of at least 1; L is an anion selected from the groupconsisting of C₁-C₂₀ alkyl, -aryl, —OR, —O—C(O)—R, NO₃—, SO₄ ²—, and PO₄³⁻; R is selected from the group consisting C₁₋₂₀ alkyl and aryl; and zis an integer of at least 1. Most preferably, the metal compound isselected from the group consisting of stannous 2-ethylhexanoate, zinc2-ethylhexanoate and mixtures thereof. Reference may be made to U.S.Pat. No. 5,093,385 (Ali), incorporated herein by reference.

[0087] If desired, the polymerization reaction may benefit from the useof polymerization modifiers such as thiuram compounds, such as thosedisclosed in Otsu, T. et al., Journal of Polymer Science: Part A:Polymer Chemistry, 1994, Vol. 32, 2911-2918, and in Otsu, T. et al.,European Polymer Journal, 1995, Vol. 31, 67-78. The addition of suchthiuram compounds is particularly useful in the polymerization ofacrylates and vinyl acetates using the photoiniferters of the presentinvention. Specifically contemplated is tetraethylthiuram disulfide.

[0088] The (co)polymers obtained by the method of the invention may bedescribed as telechelic (co)polymers comprising polymerized units of oneor more free radically (co)polymerizable monomers (as previouslydescribed), a first azlactone terminal group derived from thephotoiniferter of Formula I and a second terminal group selected fromthe group derived from dithiocarbamate. Alternatively, when using thephotoiniferters of Formula II, the first terminal group “Az” willcomprise the ring-opened residue of the azlactone group of the FormulaIII:

[0089] where R¹, R², R³, R⁴, R⁷, Z, Q, m and n are as previouslydefined.

[0090] Such (co)polymers have the general formulaAz-(M¹)_(x)(M²)_(x)(M³)_(x) . . . (M^(Ω))_(x)-DiTC, wherein “DiTC” is adithiocarbamate group of the formula R⁵R⁶N—C(S)—S—, wherein R⁵ and R⁶ asdefined in Formulas I and II; M¹ to M^(Ω) are each polymerized monomerunits derived from a radically (co)polymerizable monomer unit having anaverage degree of polymerization x, each x is independent, and Az is anazlactone group or a ring-opened azlactone group of Formula III.Further, the polymer product retains the dithiocarbamate functionalgroup “DiTC” at one terminal end of the polymer necessary to initiate afurther polymerization (or functionalization). The polymer productfurther comprises either the aziactone moiety or the ring-openedazlactone moiety of the photoiniferter at the other terminal end, whichmay be further reacted or functionalized as desired. Because the twoterminal moieties have different functionality and reactivity, eachterminus may be independently functionalized.

[0091] The terminal dithiocarbamate group may be functionalizedindependently from the terminal “Az” group. For example,functionalization of the azlactone followed by mild hydrolysis of thedithiocarbamate groups yields thiols, which readily oxidizes to form adimeric polymer linked by a disulfide group. Reduction of the disulfidelinkage to yield a thiol group, which then may be furtherfunctionalized. Further, it has been discovered that hydroxy-, amino-and thio-compounds add preferentially to the azlactone terminal grouprather than the thiocarbamate terminal group, allowing independentfunctionalization.

[0092] The present invention encompasses a novel process for preparingrandom, block, multi-block, star, gradient, random hyperbranched anddendritic copolymers, as well as graft or “comb” copolymers. Each ofthese different types of copolymers will be described hereunder.

[0093] Since photoiniferter polymerization is a “living” or “controlled”polymerization, it can be initiated and terminated as desired. Thus, inone embodiment, once the first monomer is consumed in the initialpolymerizing step, a second monomer can then be added to form a secondblock on the growing polymer chain in a second polymerizing step.Additional polymerizations with the same or different monomer(s) can beperformed to prepare multi-block copolymers. Accelerants or thiurams maybe added to control the polymerization of subsequent blocks as desired.

[0094] Because photoiniferter polymerization is radical polymerization,blocks can be prepared in essentially any order. One is not necessarilylimited to preparing block copolymers where the sequential polymerizingsteps must flow from the least stabilized polymer intermediate to themost stabilized polymer intermediate, such as is necessary in ionicpolymerization. Thus, one can prepare a multi-block copolymer in which apolyacrylonitrile or a poly(meth)acrylate block is prepared first, thena styrene or butadiene block is attached thereto, etc.

[0095] Furthermore, a linking group is not necessary to join thedifferent blocks of the present block copolymer. One can simply addsuccessive monomers to form successive blocks. Further, it is alsopossible (and in some cases advantageous) to first isolate a (co)polymerproduced by the present photoiniferter polymerization process, thenreact the polymer with an additional monomer using a thiuram oraccelerant. In such a case, the product polymer having a terminaldithiocarbamate group acts as the new photoiniferter for the furtherpolymerization of the additional monomer.

[0096] Since the novel photoiniferters provide a reactive group “Az” ata terminal end of the polymer, linking groups may be used to join twopolymer blocks. For example, in one embodiment, a polymer prepared inaccord with the present invention, and having an azlactone group at oneterminus, may be reacted with a second polymer block having anucleophilic terminal group.

[0097] Statistical copolymers may be produced using the photoinifertersof the present invention. Such copolymers may use 2 or more monomers ina range of about 0-100% by weight of each of the monomers used. Theproduct copolymer will be a function of the molar amounts of themonomers used and the relative reactivity of the monomers.

[0098] The present invention also provides graft or “comb” copolymers.Here, a first (co)polymer having pendent nucleophilic functional groups,such as hydroxy-, amino- or thio-groups, etc. is provided. An example ofuseful (co)polymers include hydroxyethyl acrylate (co)polymers. Next,the reactive functional groups of the first (co)polymer is reacted withthe azlactone photoiniferters of Formula I to provide a (co)polymerhaving pendent, ring-opened photoiniferter moieties, the reactionproduct having the structure of Formula II, where R⁷ is the residue ofthe first (co)polymer. This product (co)polymer may then be used as anphotoiniferter to polymerize the previously-described monomers toproduce a comb (co)polymer. Alternatively, the first (co)polymer may bereacted with a telechelic (co)polymer of the invention, whereby thereactive “Az” terminal group reacts with the pendent reactive group ofthe first (co)polymer.

[0099] Gradient or tapered copolymers can be produced usingphotoiniferter polymerization by controlling the proportion of two ormore monomers being added. For example, one can prepare a first block oran oligomer of a first monomer, then a mixture of the first monomer anda second distinct monomer can be added in proportions of from, forexample, 1:1 to 9:1 of first monomer to second monomer. After conversionof all monomer(s) is complete, sequential additions of firstmonomer-second monomers mixtures can provide subsequent “blocks” inwhich the proportions of first monomer to second monomer vary. Thus, theinvention provides copolymers obtained from two or more radically(co)polymerizable monomers wherein the copolymer has a composition thatvaries along the length of the polymer chain from azlactone terminus toopposite terminus based on the relative reactivity ratios of themonomers and instantaneous concentrations of the monomers duringpolymerization.

EXAMPLES

[0100] All reagents unless otherwise noted were purchased from Aldrich(Milwaukee, Wis.) and were used in their delivered condition.Polymerizable reagents were stripped of inhibitors prior to use bypassing them through an alumina column (also supplied by Aldrich).Solvents were purchased from EM Science located in Gibbstown, N.J.

EXAMPLES

[0101] All solvents and reagents were obtained, or are obtainable, fromAldrich Chemical Co., Milwaukee, Wis. Compounds described in theExamples were found to have ¹H NMR and IR spectra that were consistentwith the assigned structure.

Preparative Example 1

[0102] Preparation of 2-(2-Chloro-acetylamino)-2-methyl propionic acid.

[0103] To a stirring mixture of 2-aminoisobutyric acid (165.8 g; 1.61mol), sodium hydroxide (64.4 g; 1.61 mol) and 800 ml water cooled to 5°C., was added chloroacetyl chloride (200 g; 1.77 mol) and then asolution of sodium hydroxide (70.8 g; 1.77 mol) in 143 ml water. Thetemperature was maintained between 5 to 10° C. during the additions. Thereaction mixture was then allowed to warm to room temperature and thesolution was acidified with 165 ml of concentrated aqueous HCl. Theprecipitated solid was filtered and dried under vacuum to afford 180.4 g(62%) of product.

Preparative Example 2

[0104] Preparation of 2-Chloromethyl-4,4-dimethyl-4H-oxazol-5-one.

[0105] To a stirring mixture of 2-(2-chloro-acetylamino)-2-methylpropionic acid (18.0 g; 0.100 mol), triethylamine (11.1 g; 0.110 mol)and 100 ml of acetone in a round bottom flask, cooled with an ice bath,was added ethyl chloroformate (10.5 ml; 0.110 mol) over a period of 10minutes. The reaction mixture was then allowed to warm to roomtemperature and was stirred for 2 hours. The mixture was then filtered,and the filtrate was concentrated under vacuum. Hexane (200 ml) wasadded to the residue, and the mixture was filtered. After removal of thesolvent under vacuum, the filtrate residue was distilled under reducedpressure (59-60°; 7 mmHg) to give 13.2 g (82%) of a colorless oil.

Example 1

[0106] Preparation of Diethyl-dithiocarbamic acid4,4-dimethyl-5-oxo-4,5-dihydro-oxazol-2-ylmethyl ester (AzDC).

[0107] A mixture of 10 g of sodium diethyl dithiocarbamate trihydrateand 100 ml of toluene in a round bottom flask were boiled at refluxwhile water was separated and removed with a Dean-Stark trap. After 1hour, the mixture was allowed to cool to room temperature and thetoluene solution was concentrated under reduced pressure to afford 7.0 gof anhydrous diethyl dithiocarbamate as a pink solid, which was furtherdried in a vacuum oven.

[0108] To a solution of 6.00 g (0.037 mol) of2-chloromethyl-4,4-dimethyl-4H-oxazol-5-one dissolved in 130 ml ofacetonitrile was added 6.72 g (0.039 mol) of the anhydrous sodiumdiethyl dithiocarbamate. The mixture was stirred under a nitrogenatmosphere at room temperature for 2 hours. The reaction mixture wasfiltered, and the filtrate was concentrated under reduced pressure. Thecrude product was distilled under reduced pressure (170-180° C.; 0.25mmHg) to afford 7.46 g (74%) of AzDC as a yellow-green oil.

Example 2

[0109] Preparation of Diethyl-dithiocarbamic acid{1-[2-(bis-{2-[2-(2-diethylthiocarbamoylsulfanyl-acetylamino)-2-methyl-propionylamino]-ethyl}-amino)-ethylcarbamoyl]-1-methyl-ethylcarbamoyl}-methylester [tris(ring-opened AzDC)amine].

[0110] To a solution of 0.077 g (0.00053 mol) of tris(2-aminoethyl)aminein 10 ml of tetrahydrofuran was added 0.431 g (0.00157 mol) of theproduct of Example 1 (AzDC). The reaction was stirred at roomtemperature under a nitrogen atmosphere for 3 hours, after which timethe solvent was removed under reduced pressure. The resultant productwas dried overnight at 52° C. in a vacuum oven to afford 0.443 g (86%)of the tris(ring-opened AzDC)amine as a white powder.

Example 3

[0111] Synthesis of Az-PSt-DC via the Controlled Polymerization ofStyrene With AzDC.

[0112] A solution of 0.120 g (0.00044 mol) of the product of Example 1(AzDC, Ex. 1) in 40.0 g (0.384 mol) of styrene was prepared. Thesolution was divided into five equal 8.0 g portions, which were placedin screw-cap vials. Each vial was fitted with a screw cap that had anintegral valve and rubber septum. The solutions were degassed by threesuccessive freeze-pump-thaw cycles. The reaction vials were then placedon rollers under a UV lamp (10 cm from bulb; light intensity=1.25 mW,Sylvania F40/350BL-blacklight) and were irradiated. Each vial wasirradiated for a different period of time (2.5, 6, 10, 16 and 20 hours,respectively) after which time the reaction vial was opened and threesmall aliquots of reaction mixture were removed. Each small aliquot ofreaction mixture was weighed and was then concentrated to dryness in avacuum oven. The ratio of the mass of each dried sample to the mass ofthe aliquot of reaction mixture was used to calculate the percentconversion of the monomer. The remaining material from each reactionvial was precipitated from methanol. The resulting precipitates weredried under high vacuum, dissolved in tetrahydrofuran and analyzed bygel permeation chromatography. The results are shown in Table 1. TABLE 1GPC results for the controlled polymerization of styrene with AzDC. Time(hours) % Conversion M_(n) 2.5 7.3 15500 6 16.4 17700 10 23.2 22300 1632.7 27800 20 36.1 31000

Example 4

[0113] Synthesis of a Poly(Methyl Methacrylate) Star Polymer WithTris(ring-opened AzDC)amine.

[0114] A solution of 0.046 g (0.000047 mol) of the product of Example 2(tris(ring-opened AzDC)amine) in 100 ml of benzene was prepared. To 40.0g (0.400 mol) of methyl methacrylate in a round-bottomed flask was added11.4 ml of the tris(ring-opened AzDC)amine benzene solution. Thissolution was divided into five equal 10.0 g portions, which were placedin screw-cap vials. Each vial was fitted with a screw cap that had anintegral valve and rubber septum. The solutions were degassed by threesuccessive freeze-pump-thaw cycles. The reaction vials were placed onrollers under a UV lamp (10 cm from bulb; light intensity=1.25 mW) andirradiated. Each vial was irradiated for a different period of time (1,2, 4, 6 and 8 hours) after which time the reaction vial was opened andthree small aliquots of reaction mixture were removed. Each smallaliquot of reaction mixture was weighed and was then concentrated todryness in a vacuum oven. The ratio of the mass of each dried sample tothe mass of the aliquot of reaction mixture was used to calculate thepercent conversion of the monomer. The remaining material from eachreaction vial was dried under high vacuum, dissolved in tetrahydrofuranand analyzed by gel permeation chromatography. The results are shown inTable 2. TABLE 2 GPC results for the controlled polymerization of methylmethacrylate with tris(ring-opened AzDC)amine. Time (hours) % ConversionM_(n) 1 1.2 183,000 2 6.5 249,000 4 12.2 297,000 6 15.1 304,000 8 20.3324,000

Example 5

[0115] Synthesis of a Polystyrene Star Polymer With Az-PSt-DC andTris(2-aminoethyl)amine.

[0116] A solution of 0.163 g (0.0011 mol) tris(2-aminoethyl)amine in 750ml of benzene was prepared. In a reaction vessel, separately, a solutionof 0.478 g (0.000024 mol) of the product of Example 3 (Az-PSt-DC;Mn=19,700; polydispersity=1.76) in 4.0 ml of benzene was prepared and tothis solution was added 3.8 ml of the tris(2-aminoethyl)amine solution.The reaction vessel was capped and shook at room temperature for 18hours. Analysis of the resulting material by gel permeationchromatography showed Mn=31,500 and polydispersity=2.47. The peakobserved on the GPC chromatogram was bimodal.

Example 6

[0117] Synthesis of Az-(PSt-block-PMMA)-DC via the ControlledPolymerization of Methyl Methacrylate With Az-PSt-DC.

[0118] A solution of 0.956 g (0.000049 mol) of the product of Example 3(Az-PSt-DC; Mn=19,700; polydispersity=1.76)) in 36.6 ml of benzene wasprepared. To this solution was added 32.0 g (0.320 mol) of methylmethacrylate. This solution was divided into four equal 14.5 g portions,which were placed in screw-cap vials. Each vial was fitted with a screwcap that had an integral valve and rubber septum. The solutions weredegassed by three successive freeze-pump-thaw cycles. The reaction vialswere placed on rollers under a UV lamp (10 cm from bulb; lightintensity=1.25 mW) and irradiated. The reaction vials were eachirradiated for a different period of time (2, 3, 4 and 5 hours) afterwhich time each reaction vial was opened and three small aliquots ofreaction mixture were removed. Each small aliquot of reaction mixturewas weighed and was then concentrated to dryness in a vacuum oven. Theratio of the mass of each dried sample to the mass of the aliquot ofreaction mixture was used to calculate the percent conversion of themonomer. The remaining material from each reaction vial was analyzed bygel permeation chromatography. The results are shown in Table 3. TABLE 3GPC results for the controlled polymerization of methyl methacrylatewith Az-PSt-DC. Time (hours) % Conversion M_(n) 2 3.8 28100 3 5.6 407004 7.9 48300 5 9.8 53000

Example 7

[0119] Synthesis of Az-poly(St-co-HEMA)-DC via the ControlledPolymerization of a Styrene/2-hydroxyethyl methacrylate Mixture WithAzDC.

[0120] A mixture of 0.030 g (0.00011 mol) of AzDC, 0.497 g (0.0038 mol),2-hydroxyethyl methacrylate (HEMA) and 9.98 g (0.096 mol) of styrene wasprepared in a screw cap vial that was fitted with a cap that had anintegral valve and rubber septum. The mixture degassed by threesuccessive freeze-pump-thaw cycles. The reaction vial was then placed onrollers under a UV lamp (10 cm from bulb; light intensity=1.25 mW) andirradiated. The reaction mixture was irradiated for 16 hours. Uponcompletion of the irradiation, the resulting material was precipitatedfrom petroleum ether. The resulting precipitate was dried under highvacuum, dissolved in tetrahydrofuran and analyzed by gel permeationchromatography. The resulting polymer had Mn=25,200 andpolydispersity=1.97.

Example 8

[0121] Synthesis of a Branched Copolymer With Az-poly(St-co-HEMA)-DC.

[0122] The product of Example 7 (Az-(St-co-HEMA)-DC; 1.25 g; 0.000050mol) was dissolved in 1.5 ml of tetrahydrofuran in a screw-cap vial. Tothis solution was added 7.5 μL (0.000050 mol) of1,8-diazabicyclo[5.4.0]undec-7-ene (DBU). The vial was shaken at roomtemperature on a laboratory shaker for 18 hours. Analysis of theresulting material by gel permeation chromatography showed Mn=37,500 andpolydispersity=4.05.

We claim:
 1. A photoiniferter of the formula:

wherein R¹ and R² are each independently selected from H, an alkylgroup, a nitrile, a cycloalkyl group, a heterocyclic group, an arenylgroup and an aryl group, or R¹ and R² taken together with the carbon towhich they are attached form a carbocyclic ring; R³ and R⁴ are eachindependently selected from an alkyl group, a cycloalkyl group, an arylgroup, a heterocyclic group, an arenyl group, or R³ and R⁴ takentogether with the carbon to which they are attached form a carbocyclicring; R⁵ and R⁶ are each independently selected from an alkyl group, acycloalkyl group, a heterocyclic group, an aryl group, an arenyl group,or R⁵ and R⁶ taken together with the nitrogen to which they are attachedform a heterocyclic ring; R⁷ is an organic or inorganic moiety and has avalency of m; Z is —O—, —S—, or —NR⁸ wherein R⁸ can be a H, an alkyl, acycloalkyl or aryl, a heterocyclic group, an arenyl, m is at least 1; Qis a linking group selected from a covalent bond, an aryl group,(—CH₂—)_(o), —CO—O—(CH₂)_(n)—, —CO—O—(CH₂CH₂O)_(o)—, —CO—NR⁸—(CH₂)_(n)—,—CO—S—(CH₂)_(o)—, where o is 1 to 12, and R⁸ is H, an alkyl group, acycloalkyl group, an arenyl group, a heterocyclic group, or an arylgroup; and n is 0 or
 1. 2. The photoiniferter of claim 1 wherein atleast one of R₁ and R₂ is a C₁ to C₄ alkyl group.
 3. The photoiniferterof claim 2 wherein at least one of R₁ and R₂ are methyl.
 4. Thephotoiniferter of claim 1 wherein at least one of R₃ and R₄ is a C₁ toC₄ alkyl group.
 5. The photoiniferter of claim 4 wherein R₃ and R₄ aremethyl.
 6. A method for addition photopolymerization of one or moreolefinically unsaturated monomers comprising exposing a mixture of oneor more olefinically unsaturated monomers and the photoiniferter ofclaim 1 to actinic energy.
 7. The method according to claim 6, whereinthe olefinically unsaturated monomers are selected from (meth)acrylicacid and esters thereof, fumaric acid and esters thereof, itaconic acidand esters thereof, maleic anhydride; styrene, α-methyl styrene; vinylhalides; (meth)acrylonitrile, vinylidene halides; butadienes;unsaturated alkylsulphonic acids and esters and halides thereof; and(meth)acrylamides, and mixtures thereof.
 8. The method according toclaim 6, wherein the polymerization is conducted neat or in a solvent.9. The method of claim 8 wherein said solvent is selected from ethers,cyclic ethers, alkanes, cycloalkanes, aromatic hydrocarbon solvents,halogenated hydrocarbon solvents, acetonitrile, mixtures of suchsolvents, and supercritical solvents.
 10. The method according to claim6 further comprising a second polymerizing step using one or moreadditional olefinically unsaturated monomers.
 11. The method of claim 6,wherein the photoiniferter is present in a concentration of from 10⁻⁵ Mto 1 M.
 12. The method of claim 6, wherein the molar ratio ofphotoiniferter and monomer(s) is from 10⁻⁵:1 to 10⁻¹:1 of photoiniferterto monomer(s).
 13. The method of claim 6, wherein said mixture furthercomprises an accelerant of the formula M_(y)L_(z) wherein M is a cationhaving a valency of z of a metal which is selected from the groupconsisting of tin, zinc, cobalt, titanium, palladium, and lead; y is aninteger of at least 1; L is an anion which is selected from the groupconsisting of C₁-C₂₀ alkyl, -aryl, —OR, —O—C(O)—R, NO₃—, SO₄ ²⁻, and PO₄³; R is selected from the group consisting C₁₋₂₀ alkyl and aryl; and zis an integer of at least
 1. 14. The method of claim 6 furthercomprising a thiuram compound.
 15. A telechelic (co)polymer comprisingpolymerized units of one or more free radically (co)polymerizablemonomers, an first ring-opened azlactone terminal group; and a seconddithiocarbamate terminal group.
 16. The copolymer of claim 15 comprisingtwo or more blocks of units obtained from free radically(co)polymerizable monomers, wherein the block copolymer has anring-opened azlactone residue at one terminal end and a dithiocarbamategroup at the other terminal end.
 17. The (co)polymer of claim 15comprising polymerized units obtained from two or more radically(co)polymerizable monomers wherein the copolymer has a composition thatvaries along the length of the polymer chain from ring-opened azlactoneterminus to opposite terminus based on the relative reactivity ratios ofthe monomers and instantaneous concentrations of the monomers duringpolymerization.
 18. The (co)polymer of claim 15, wherein said(co)polymer comprises polymerized monomer units selected from the groupconsisting of (meth)acrylic acid and esters thereof; fumaric acid andesters thereof; itaconic acid and esters thereof; maleic anhydride;styrene; α-methyl styrene; vinyl halides; (meth)acrylonitrile,vinylidene halides; butadienes; unsaturated alkylsulphonic acids andesters and halides thereof; and (meth)acrylamides, and mixtures thereof;said (co)polymer having an azlactone residue at one end of the(co)polymer chain and a radically transferable group at the other end ofthe (co)polymer chain.
 19. The (co)polymer of claim 15 having thestructure Az-(M¹)_(x)-DiTC, wherein DiTC is a dithiocarbamate of theformula R⁵R⁶N—C(S)—S, where R⁵ and R⁶ are each independently selectedfrom an alkyl group, a cycloalkyl group, a heterocyclic group, an arylgroup, an arenyl group, or R⁵ and R⁶ taken together with the nitrogen towhich they are attached form a heterocyclic ring; M¹ is a monomer unitderived from a radically (co)polymerizable monomer unit having anaverage degree of polymerization x, and Az is a ring-opened azlactonegroup of the formula:

wherein R¹ and R² are each independently selected from H, an alkylgroup, a nitrile, a cycloalkyl group, a heterocyclic group, an arenylgroup and an aryl group, or R¹ and R² taken together with the carbon towhich they are attached form a carbocyclic ring; R³ and R⁴ are eachindependently selected from an alkyl group, a cycloalkyl group, an arylgroup, a heterocyclic group, an arenyl group, or R³ and R⁴ takentogether with the carbon to which they are attached form a carbocyclicring; R⁷ is the residue of a mono- or polyfunctional compound of theformula R⁷(ZH)_(m); Z is —O—, —S—, or —NR⁸ wherein R⁸ can be a H, analkyl, a cycloalkyl or aryl, a heterocyclic group, an arenyl and m is atleast one; Q is a linking group selected from a covalent bond,(—CH₂—)_(o), —CO—O—(CH₂)_(o)—, —CO—O—(CH₂CH₂O)_(n)—, —CO—NR⁶—(CH₂)_(o)—,—CO—S—(CH₂)_(o)—, where o is 1 to 12, and R is H, an alkyl group, acycloalkyl group, an arenyl group, a heterocyclic group or an arylgroup; and n is 0 or
 1. 20. The (co)polymer of claim 15 having thestructure Az-(M¹)_(x)(M²)_(x)—(M³)_(x) . . . (M^(Ω))_(x)-DiTC, whereinDiTC is a dithiocarbamate of the formula R⁵R⁶N—C(S)—S, where R⁵ and R⁶are each independently selected from an alkyl group, a cycloalkyl group,an aryl group, an arenyl group, or R⁵ and R⁶ taken together with thenitrogen to which they are attached form a heterocyclic ring; M¹ toM^(Ω) are each polymer blocks of monomer units derived from a radically(co)polymerizable monomer units having an average degree ofpolymerization x, each x is independent, and Az is a ring-openedazlactone group of the formula:

wherein R¹ and R² are each independently selected from H, an alkylgroup, a nitrile, a cycloalkyl group, a heterocyclic group, an arenylgroup and an aryl group, or R¹ and R² taken together with the carbon towhich they are attached form a carbocyclic ring; R³ and R⁴ are eachindependently selected from an alkyl group, a cycloalkyl group, an arylgroup, an arenyl group, or R³ and R⁴ taken together with the carbon towhich they are attached form a carbocyclic ring; R⁷ is the residue of amono- or polyfunctional compound of the formula R⁷(ZH)_(r); Z is —O—,—S—, or —NR wherein R can be a H, an alkyl, a cycloalkyl, an aryl group,a heterocyclic group, an arenyl and m is at least one; Q is a linkinggroup selected from a covalent bond, (—CH₂—)_(o), —CO—O—(CH₂)_(o)—,—CO—O—(CH₂CH₂O)_(o)—, —CO—NR⁸—(CH₂)_(n)—, —CO—S—(CH₂)_(o)—, where o is 1to 12, and R⁸ is H, an alkyl group, a cycloalkyl group, an arenyl group,a heterocyclic group or an aryl group; and, m is at least one and n is 0or 1.